Power hammer



April 14, 1931.A F. P. MILLER ET AL 1,890,465

' POWER HAn/IMERl Filed March 14, 1927 2 Sheets-Sheet l ew/5 fleet) me; f' I abbo/:nag

April 14, 1931. F. P.' MILLER ET AL 'I 1,800,465

y POWER HAIVIMER Filed March 14, '1927' '2 Sheets-.Skaten` 2 nIl? Patented Apr. 14, 1931 UNITEDSTATES PATENT 'ori-ICEg FRANK r. MILLER AND .LEWIS sKnEL, on

MEADVILEQ PENNSYLVANIA,Y ASSIGNORS y'.l'O MGCROSKY TOL CORPORATION, 0F ITADVILLE, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA POWER HAIJIMER l 'Application med Maren 14, 1927. serial No. 175,242. f

This invention relates'to power'operated hammers ofthe type in which av compressible power transmitting medium is employed betweenthe'driving and Vdriven members.

Briefly stated an important-object of this V,invention is to provlde an air hammer in which the construction of parts isV such that the'cost of manufactur-e is substantially reduced as compared with other hammers of which we know and in which novel means are provided to avoid loosening of various parts of the hammer as ay result of vibration incldent to use. f

Another equally important aim is to pro- '15 vide a hammer ofthe character specified In .the accompanyingdrawings forming a part ofthis applicationv and in. which like numerals are *employedH to designate n like parts throughout the same:

Figure 1 is a longitudinaly sectional view through the hammer.

7 35 Figure 2 is asimilar view takenat lright angles to Figure 1. y f l Figure 3 is 4a transverse sectional view l taken on lineB-f of Figure 1. A 1'.'

3a is a sectional view througha modi- 4 nemen.' l y f Figure 4 is a longitudinal sectional view illustrating a slight' modification of the invention. i Figure 5 is a detail sectional. view illustrating another .expression of the invention.

Figure .6 is an end view ofthe intermediate piston illustrated in Figure'. Figures? is a detail longitudinal sectional -view through a further modification of the invention.

' enough toextend into the inner tubular memn ber defined byy Figure Sisan end viewoflthe intermediate piston illustrated in Figure 7. Y

In th drawingsthe numerals 1() 'and 11 designate inner and outer closely interfitting tubular ymembers `which together form the y barrel of thehammerand which are connected at therear portions thereof to the annularclamp 12 ofa housing 14.r Figure 3 clearly illustrates that the housing is provided with a pair of aligned apertured ears 15 rreceiving a bolt 16 having a nut 17 by which the clamp 12 may be secured in binding engagement with the barrel. Figure 1 illustrates that the bolt 16 extends through a' transverse groove'18 in the outer tube 11 to positively hold the barrel against turning and endwise shifting as a vresult of the vibration to which tools of this character are known `to be subjected. Theillustrated connection u between the barrel and the clamp 12 avoids the necessity of employing interiitting l threads which are likely to loosen because of vibration. yAs ,suggested in Figure *3a the transverse groove v180 may be made `deep ber 10- to permit the bolt 16 to have binding engagement with both'the tubes 10 and 11.l

The Louter tube 11 extends to a point well in advance of the inner'tube 10 and is. peened or flanged inwardlyas indicated atv19'to limit the forward movement of a tool holding nib 20. The nib 20 has a centrall longitudinally extending opening for vthe reception of the attaching kportion 21of a tool 22 and by reference to Figure 1 it will be seen that the attaching lportion 21 terminates at a point rearwardly of the nib so the same may receive the power blowsV of a driven piston 24. `In carrying outthe invention the driven piston 24 and the driving piston 25 are mounted to lreciprocate within the inner tube V10 so that the air compressed on the forward stroke of the driving piston is utilized to advance the driven piston in much the same lmanner as many other pulsating 'hammers-95 vIn more specifically alluding to this feature,

however, it might be pointed out that the forward stroke of the' driving piston com'- presses'the air in the mainy compressionchamthe two pistons so that this" CFI compressed air acts as a power transmitting medium by which the driven piston 24 is caused to strike the rear end of the tool shank 2l. On the rear stroke of the driving piston 25 a vacuum is created between the two pistons so that the driven piston is retracted.

Figure Vl illustrates that the driving piston 25 is provided with a supplemental compression chamber 26 adapted to snugly receive a cylindrical extension 27 on the rear end of ythe driven member. The air Within the chamber 26 is compressed on the forward stroke of the driving piston and the resulting pressure against the extension 27 adds to the force of the blow.

Figure l illustrates the various parts of the hammer in a neutral position so that reciprocation of thefdriving piston 25 will have no effect on the driven piston 24. However, should it be desired to operate the tool for .its intended purpose the operator has only `to bring the member 22 intoY pressure contact with the work such as a rivet or a rock so vthat the nib 2O will be retracted Vagainst the influencel of a coil spring 28. By thus moving the tool forwardly into pressure contact with the work the piston 24 is moved rearwardly in the barrel to close or partly close the ports` 29 depending, of course, on the degree of forward pressure `exerted by the operator. In case only a very slight forward pressure is Vexerted by the operator on the tool the piston 24 will be moved partly over the ports 29 so that'the reciprocation of the piston 25, will through the medium of the lightly compressed air, advance the piston 24 with only limited force into engagement with the shank 21.

ed to, the forward pressure exerted by the op- Y erator on the tool is increased so that the piston 24 will be caused more completely to close the ports 29. To secure the full force of the blow it is only necessary to exert suflicient forward pressure to cause the piston 24 to entire- 1` ly close the ports 29.

Attention is especially invited to the factY that the ports 29 increase in area toward the rear ends thereof to provide for the sensitive control of thedriving connection between the two pistons. Y A

The intermediate portion of the nib 20 is annularly enlarged to define a pair'of shoulders, the forward` one of which cooperates Ywith the inwardly peened terminal of the tube l1, while theV rear shoulder of the annular enlargementis engaged by the forward portion of the spring 28. It will be seen that the spring 28 holds the'nib 20 and the tool 22 in fullyadvanced position when the apparatus is not in active use whereby reciprocation of the driving piston will have no effect.

' Also the spring assists the operator in con- V trolling the `extent to which' the tool 22, the nib 20 and the piston 24 are moved backward 1,eoo,465

yrearward movement of the tool to the nib 20 and also limits the extent to which therear terminal of the shank 2l projects beyond the rear end of the nib. lhus it is that the nib 20 is mounted for free `movement in the forward portion of the tube l1V and `may be moved rearwardly against the tension of the coil spring 28 only by the exertion of forward, pressure on the toolby the operator to control the degree ofl response of the driven piston to the reciprocation of the driving piston as suggested in the opening paragraphs of this specification.

One of the most important features of the invention resides in the fact that the tube 10 is externallyand longitudinally grooved as Vindicated at 32 to cooperate with the outerV tube 1l in the formation of air conduits, they inner tube being provided with Vthe ports 29 and Vports 33 in communication with these grooves to permit of the easy flow` of air under the influence of the several pistons.

' In further alluding to the above feature it is pointed out that `on the rear Strokes of the driving and driven piston the air rearwardly of the driving piston may travel forwardly through the grooves 32 and enter the tube l0 through ports 33 in advance of the driven piston to avoid the formation of a vacuum in advance of the piston and in fact to aid in the Y Y n rearward movement of the driven piston; In case the force of the blow is to be addl VThe driving pistonhas universal connection with a pitman rod 31, the rear portion of which receives the interfitting crank pins 34 of a pair'of driving disks 35. The driving disks are counter-balanced to avoidunnecessary vibration. Y

The disksare provided with laterally projecting spindles 36 and 37 mounted on antifriction elements 38,v one of the anti-friction elements: being carried by the fixed side of the housing 14 while the other one is carried by a detachable side plateA 39. At :this point it might be stated that the side: plate 39 is threaded into placeand is held by a set screw 40 against loosening as a result of vibration. Figure l clearly illustrates that the set screw has the forward portion thereof..4 somewhat tapered forv engagement with the chamfered edge of the opening into'which the side plate 39 is threaded. The firm engagement of the set screw 40 with 'the' chamfered edge of the opening will positively holdi the side plate against turning. r f

The improved hammer is provided with a handle 42 having an attaching plate 43 designed to be held in place by the cap screws 44 or other suitable means. It is important lterminates beyond to note that the openings in the attaching plate 43 freely receive the Shanks of the cap screw 44 to permit of a limited movement of' the handle with respect to the remainder of the tool. Figure 2 illustrates that a pad of rubber, cork or other yieldable material is interposed between the attaching plate 43 and the adjacent portion of the housing 14 to reduce the shock on the operator to a minimum. In lieu of a pad as illustrated a bowed spring may be employed.

The spindle 37 is the fixed hub 46 ofthe side plate 39 and is longitudinally socketed to receive the attaching portion of a flexible or other driving unit. Driving pinsl 47 are extended across the longitudinal socket in the spindle 37 and have flats adapted to be engaged by the flattened surface of the driving member. By this construction the turning of the driving member such as a flexible shaft will result in the turning of the spindle 37 and in the reciprocation of the piston 25.

The fixed hub 46 is provided with radial lugs 81 by which the coupling of a flexible chain or the like may be detachably connected to the hammer.

Attention is invited to Figure 4 which illustrates that the driving piston 49 may be provided with a central extension 50 adaptedl to be snugly received in a supplemental compression chamber 51 in the rear end portion of the driven piston 52. It will be observed'that the other parts of the hammer may be much the same as the hammer illustrated in Figures 1 and 2.

In the form of invention illustrated in Figures 5 and 6 both the driving and driven pistons 53 and 54 are provided with axial reduced extensions 55 and 56 adapted to be snugly received in supplemental compression chambers 58 in a freeintermediate piston 59. Figure 6 illustrates thatthe free intermediate piston 59 is provided with longitudinal grooves 60 by which the pressure in the spaces at opposite ends of the free intermediate piston is equalized on the power stroker of the driving piston andeby which the vacuum at both ends of theintermediate piston is equalized during the retraction of the driving piston.

'Figures 7 and 8 illustrate still another me-l extended through and tainer, a tool holding nib slidable within the extended portion ofvsaid outer tubular memv ber andv being provided with a shoulder cooperating with said retainer in limiting endwise movement 'of the nib, a spring confined Y between said shoulder and the forward terminal of the inner tubular member, said inner tubular memberk being provided with a port for the discharge of air, a piston within said barrel and adapted to control said port, and means" carried solely by and movable with said piston with respect to said port.

2. A power hammer comprising a barrel, driving and driven pistons within said barrel, and a free intermediate piston between said driving and driven pistons, said free intermediate piston being provided with .a passage for air, said passage communicating with the spaces at opposite ends of the intermediate piston.

3. A power having a main chamber, pistons in said chamber, and an intermediate piston between said driving and driven pistons and having means establishing communication with the spaces at the opposite ends of the intermediate piston, said chamber being adapted for the reception of a compressible fluid by which power is transmitted from the driving to the driven piston.

In testimony whereof we aiiix our signatures.

FRANK P. MILLER.

LEWIS SKEEL.

chanical expression ofthe invention as the y driving and driven piston 61 and 62 respectively are provided with aligned vsupplemental chambers 63 and 64 respectively to snugly receive the reduced end portions of the free intermediate piston 65. The piston 65 is provided between the ends thereof'with longitudinal grooves 66 by which the pressure as well as the vacuum is equalized during the operation of the hammer. The grooves 66 also allow of the passage of the air through the ports 2.9 when the driven pis- Y driving and driven ias 

